With continuous development of display technology, many kinds of light emitting components have been applied in a display apparatus. An organic light emitting diode (OLED) is a very common light emitting component in the display apparatus. A display apparatus based on the OLED light emitting component has become popular due to advantages that it is light and thin, has a low power consumption, wide viewing angle, and fast response.
In the OLED display apparatus, the OLED comprises a multi-layer structure. Generally, the multi-layer structure comprises an anode, a hole transport layer, a light emitting layer, an electron transport layer, and a cathode. In a feasible production process, the anode is formed on a substrate. Then, the hole transport layer, the light emitting layer, and the electron transport layer are in sequence arranged over the anode by a film forming process (e.g., vacuum thermal evaporation, organic vapor deposition, or the like). Finally, the cathode is arranged as a topmost layer, and the OLED of a multi-layer structure is completed. Generally, each OLED is divided into a plurality of light emitting units, each of which comprises a light emitting layer of a primary color.